Hot wire starting switch for singlephase induction motors



NOV. 3, J ENBERGER HOT WIRE STARTING SWITCH FOR SINGLE-PHASE INDUCTIONMOTORS Filed April 21, 1961 4 Sheets-Sheet 1 N MOTORS 1964 J.ELLENBERGER HOT WIRE STARTING SWITCH FOR SINGLEPHASE INDUCTIO 4Sheets-Sheet 2 Filed April 21, 1961 Nov. 3, 1964 J. ELLENBERGER3,155,796

HOT WIRE STARTING SWITCH FOR SINGLE-PHASE INDUCTION MOTORS Filed April21, 1961 4 Sheets-Sheet 3 Nov. 3, 1964 J. ELLENBERGER 3, 9

HOT WIRE STARTING SWITCH FOR SINGLE-PHASE INDUCTION MOTORS Filed April21. 1961 4 Sheets-Sheet 4 United States Patent M 3,155,796 H01 WERESTARTING 5WITH FQR SENGLE- PHASE INDUQTHJN MGTQRS .l'ahob Ellenherger,Ziegelweg 632, Aitdorf, near Nnrnherg, Germany Filed Apr. 21, M61, Ser.No. 1il4,655 Claims priori" application Germany, Apr. 23, 1966, E19,249; Apr. 15, 1961, E 26,933 3 Qlaims. (Cl. zen-r22 The presentinvention relates to a starting switch for single-phase induction motorswhich is provided with a pivotable contact carrier, the contact of whichseparates from its associated contact when the rated speed of the motoris reached, and with a heating wire lying in the motor circuit, one endof which is secured to a pivotable lever which is acted upon by a springand is connected to the contact carrier.

A known starting switch of the type has a pivotable lever which isconnected not only to the contact carrier of the starting switch, butalso to the contact carrier of a motor-protective switch. This knownswitch therefore constitutes a combination of a starting switch with amotor-proteotive switch. This requires that the heating wire must be ofvery accurate dimensions so that both switches will be reliably releasedseparately from each other. Furthermore, the contact carrier and theheating \m're of this known starting switch extend at an oblique angleto each other and are offset relative to each other. This arrangementhas the disadvantage that the size of the switch will thereby beincreased.

It is the object of the present invention to provide a starting switchof the above-mentioned type which may be produced in a very simplemanner and may be made small in size. in order to attain this object,the present invention provides that the contact carrier and the heatingwire are arranged substantially parallel opposite to each other and thatthe pivotable lever is made in the form of an angular lever, one arm ofwhich extends vertically to the contact carrier and to the heating wireand the free end of which is connected to the heating wire, while theother arm extends in the direction of the contact carrier and isconnected thereto.

The contact carrier, the heating wire, and the angular lever of theswitch according to the invention togcther form approximately arectangle which substantially defines the size of the switch. The switchaccording to the invention may therefore be made of a very compact size.This is very important in a starting switch since it must be mountedeither on the single-phase induction motor or within the housing of thismotor.

In order to simplify the production or" the switch, the inventionfurther provides that the contact carrier and the associated arm of theangular lever will be made of one piece. The contact carrier then formsthe longer arm of the angular lever, while the shorter arm. forms theconnection to the heating wire. The angular lever is pivotably mountedat a point near the point of engagement of the heating wire. Thus, along lever arm will be formed for the movable contact.

Due to the arrangement of the movable contact on the end of the long armof the angular lever, a relatively large transmission ratio will beattained between the point of engagement of the heating wire on theshort arm of the angular lever and the contact of the angular lever sothat a large connecting movement will be attained even though theheating wire expands for only a small distance.

in order to attain a pivoting movement of the angular lever with aslittle inertia as possible when the heating wire is heated, the longerarm of the angular lever which forms the contact carrier is recessedwhereby the cross Patented Nov. 3, 1964 sectional area of this long armas well as the weight thereof will be reduced.

According to a further feature of the invention, the angular lever maybe arranged so that, when the main winding and the heating wire which isconnected in series therewith are without current, the contact carrierwill be located in the disconnecting position, while when the heatingwire is heated by the strong starting current, the contact carrier willbe moved to the connecting position. When the heating wire is cold, thecontact of the contact carrier therefore does not engage with itsassociated contact. The heating wire will therefore not be expandeduntil heated by the high starting current, and it will then be expandedto such an extent that the contacts of the angular lever will engageunder the action of a spring after approximately one to two seconds withthe associated contact, whereby the starting winding will be suppliedwith current. The motor can then run up to its rated operating speed. Assoon as the motor has reached its rated speed, the starting current willdecrease automatically to the strength of the normal operating currentwhich is not suflicient to expand the heating wire to such an extentthat the contact of the contact carrier will further remain inengagement with the associated contact. The contact of the contactcarrier therefore separates from the associated contact after the motorhas started to run and it remains in this position during the entireoperaion during which the starting winding is also disconnected. Ifduring the starting any kind of disturbances occur in the startingswitch according to the invention which may delay the startingprocedure, for example, by an overload, the starting winding will not bedisconnected until the starting has been completed since the actuationof the starting switch depends upon the size of the motor current.

For simplifying the manufacture and installation of the starting switchaccording to the invention, the shorter arm of the an ular lever ispivotably mounted on the edge of a bent portion of a terminal stripwhich is secured to a supporting plate of insulating material. Thisresults in a simple mounting of the angular lever and also in a savingof material so that the switch according to the invention may be made ofa small size. For actuating the angular lever when the heating wireexpands, a compression spring is provided which acts upon the shorterarm of the angular lever at the side of its mounting opposite to theheating wire, while the other end of the spring rests on a bent portionof the terminal strip. This construction also assists in making theswitch according to the invention of a small size.

According to a further embodiment of the invention, a contact springwhich carries the contact which is associated with the contact of theangular lever is arranged parallel to the longer arm of the angularlever in a rectangular configuration. The contact spring may be securedby means of a rivet or a single spot weld to an angular arm of a secondterminal strip which is secured to the supporting plate, and it may besecured in its position on this arm at both sides of it place ofsecurement by means of projections which are pressed out of the angulararm.

In order to attain an accurate adjustment of the tension of the heatingwire and of the distance between the contact of the angular lever andits associated contact, the invention further provides that the otherend of the heating wire is connected with an angular member, one arm ofwhich secures the heating wire and is pivotably mounted at its free endon or adjacent an end of a bent portion of a third terminal strip whichis secured to the supporting plate, while the other arm thereof carriesa micrometer adjustment screw, the end of which engages upon the bentportion of the third terminal strip. When ml? the adjustment screw isturned in one or the other direction, the tension of the heating wirewill be either increased or reduced with respect to the compressionspring of the angular lever, and at the same time an accurate adjustmentwill be made of the distance between the contact of the angular leverand the associated contact on the contact spring.

For reliably preventing the heating wire from being overheated, theinvention further provides protective means comprising an additionalcontact on the side of the associated contact which is mounted on thecontact spring, that is, on the side opposite to the contact on theangular lever. If the heating wire is heated considerably and expandedaccordingly, the contact on the angular lever presses under the actionof the compression spring the associated contact against this furthercontact, so that the heating wire will thereby be short-circuited andwill then be able to cool off. The heating of the heating wire will thusbe limited and it will be absolutely prevented from being overheated.According to another feature of the invention, the supporting plate onwhich all parts of the switch according to the invention are secured isdisposed vertically to a base plate and is made integral therewith.According to another feature of the invention, the heating wire ismounted parallel to and in the vicinity of these two plates. Since greattensions may occur in the heating wire, the one-piece construction ofthe two plates and their angular arrangement to each other insure thatthese tensions of the heating wire will be safely taken up. In order toincrease the stability of this embodiment of the starting switchaccording to the invention, the rib is molded on the supporting plateparallel to the heating wire and to the base plate. This rib supportsthe bent portion which serves for mounting the angular lever. Forsimplifying the production of the switch, the bearings for the angularlever and the angular member are produced by stamping.

According to a further feature of the invention, the contact carrier ismade in a manner known as such in the form of a snap element which isprovided with a tilt-' ing member which is acted upon by the arm of theangular member which faces toward this member. Such a snap element hasthe advantage that it permits a delay of the connecting anddisconnecting processes, either of which does not occur until thetilting point has beenexceeded.

In starting switches with heating wires which are provided with acontrol element which is not a snap element, the following disadvantagesmay occur. If the starting switch is designed so that in the cold stateof the heating wire the movable contact is in engagement with theassociated contact, it may occur that the heating wire will becomeheated so quickly that the starting circuit will be switched off beforethe motor has run up to its normal operating speed. If the switch isdesigned so that when the heating wire is cold, the movable contact doesnot engage with the associated stationary contact and only engagestherewith when the heating wire is heated, it may occur when theauxiliary phase is disconnected that the discharge current impulse ofthe starting condenser will heat the very sensitive heating wire andexpand the same to such an extent that the contacts will be closed andthe starting circuit will again be connected. These disadvantages willbe reliably prevented by means of the snap element. The heating wiremust expand for a longer period of time before the tilting point of thesnap element will be reached. Furthermore, the discharge current impulseof the condenser will then not be sutlicient at the time when thestarting circuit is being disconnected to heat and expand the heatingwire to such an extent that the contacts will again be closed.

According to another feature of the invention, the tilting member ismade in the form of a bent leaf spring and is mounted at one end thereofin a substantially V- shaped recess in the other arm of the angularlever, while the other end of the leaf spring engages upon an dge of anaperture in the contact carrier. When the heating wire is heated, itwill expand and thereby release the angular lever so that the latter canturn under spring action about its pivot point, whereby the leaf springwill be moved beyond its tilting point and the contact carrier willthereby he suddenly pivoted to its disconnecting posi tion.

In order to reduce the weight of the contact carrier to a minimum, theaperture therein is enlarged up to a point near the end of the contactcarrier facing away from the contact. The rear inner edge of theaperture is then utilized for pivotably mounting the contact carrier.For this purpose, this inner edge engages into a substantially V-shapedrecess from the outer side of the arm of the angular lever which extendsvertically to the heating wire or to contact carrier, and in thevicinity of the vertex of the angular lever. The contact carrier itselfmay be made of a leaf spring, although it does not have to exert anyspring action since it is merely subjected to tension by the tiltingmember which is made in the form of a bent leaf spring. Directlyunderneath the V-shaped recess, the angular lever is mounted in avertical bent portion of a terminal strip. For this pivotable mountingthe angular lever is provided with lateral notches into which thelateral edges of. an aperture in the vertical bent portion of theterminal strip engage. By this construction it is possible to simplifythe manufacture as well as the installation of the starting witchaccording to the invention.

For tightening the heating wire and for actuating the angular lever acompression spring is provided, one end of which engages upon theangular lever underneath the notches, while the other end engages upon avertical part of the vertical bent portion of the terminal strip. Thecompression spring is mounted in this manner so as to be well protected.

In order to permit an accurate adjustment of the tilting point of thesnap member or of the pivoting distance of the angular lever, anadjustable screw which in the disconnecting position of the contactcarrier engages upon a stop is screwed in the vicinity of the tiltingmember into the arm of the angular lever which faces toward the contactcarrier. The tilting point of the snap member or the pivoting distanceof the angular lever may also be influenced by a tightening device forthe heating wire. This tightening device is provided with a lockableslide member on which one end of the heating wire is secured and whichis slidable in the direction of the heating wire. This slide member isguided between vertical bent portions on a second terminal strip. Thesevertical portions are arranged in a space saving manner between thecontact carrier and the heating wire. This arrangement contributes tothe desired result that the starting switch according to the inventionwill be as small as possible. ment of the slide member and thus of thetension of the heating wire, this slide member is provided with a bentportion which extends transverse to the sliding direction and into whicha screw is inserted which engages into a recess in the bent portion ofthe second terminal strip. Since the screw for the adjustment of theslide member engages into a recess .of the bent portion, the advantageis attained that the slide member will be held at the bent portion sothat a lateral shifting of the slide member will be reliably prevented.slide member from tilting, one of 'the bent portions of the secondterminal strip is provided with an angular portion which surrounds theslide member at its inner end.

This insures a reliable and simple guiding oftheslide member at the bentportions of the second terminal strip. I

One of the bent portions of the second terminal strip is provided withthe stop for the screw which is secured According to a furtherembodiment it in the angular lever. of the invention, this stop may alsoform a contact.

In order to permit a very accurate adiustin order to prevent the theadjustment screw which is secured in the angular lever engages upon thiscontact, the heating wire will be short-circuited through the angularlever and the slide member so that the heating wire will thus beprevented from overheating, since after being short-circuited it willcool off.

According to another feature of the invention, the terminal strips formthe supports of all parts of the switch mechanism and they are securedto a plate of insulating material which forms a part of the housing. Theterminal strips may, for example, be secured to the plate in a simplemanner by means of hollow rivets. According to another feature of theinvention, the plate is provided within the area of the end of thecontact carrier carrying the contact with two vertical projections whichare integral therewith and one of which serves as a stop for the contactcarrier in its disconnected position.

The various features and advantages of the invention will become furtherapparent from the following description which is to be read withreference to the accompanying drawings in which- FIGURE 1 shows a sideview of a starting switch according to the invention in the openedposition;

FIGURE 2 shows a cross section taken along line IIII of FIGURE 1 throughthe closed switch;

FIGURE 3 shows the same view as FIGURE 1 with the switch element in theconnecting position;

FIGURE 4 shows the switch according to FIGURE 1 as seen from above;

FIGURE 5 shows a cross section taken along line VV of FIGURE 1;

FIGURE 6 shows a front View of the closed switch according to FIGURE 1in its substantially actual size and as seen in perspective;

FIGURE 7 shows a perspective rear view of the switch according to FIGURE6;

FIGURE 8 shows a circuit diagram of the switch according to FIGURE 1with the windings of an electric motor;

FIGURE 9 shows a plan view of a modification of the starting switchaccording to the invention in the connected position and without thehousing cap;

FIGURE 10 shows the switch according to FIGURE 9 as seen from the leftthereof, in which the housing cap is applied and shown in cross section;

FIGURE 11 shows the same plan view as FIGURE 9 but with the switch inits disconnecting position;

FIGURE 12 shows a cross section taken along line XIIXII of FIGURE '9;

FIGURE 13 shows a cross section taken along line XIII-XIII of FIGURE 9;

FIGURE 14 shows a perspective view of the switch according to FIGURES 9to 13 without the housing;

FIGURE 15 shows a perspective view of the closed switch according toFIGURES 9 to 13 in its natural size;

FIGURE 16 shows a perspective view of the lower side of the switchaccording to FIGURE 15;

FIGURE 17 shows a circuit diagram of the switch according to FIGURES 9to 16 together with the main and auxiliary windings of a single-phaseinduction motor;

FIGURE 18 shows a circuit diagram similar to that of FIGURE 17, but inwhich the main winding is connected to a different terminal strip; WhileFIGURE 19 shows a plan view of a further modification of the startingswitch according to the invention in the disconnecting position withoutthe housing cap, and in which the heating wire is shown in the coldposition.

The starting'switch as illustrated in FIGURES l to 7 comprises a housingwhich consists of a supporting plate 1 and a base plate 2 integraltherewith and made of an insulating material, for example, moldedplastic, and of a cover 3. This cover 3 is secured to supporting plate 1by means of a screw 4 and a nut 5. By providing the base plate 2 and thesupporting. plate I as well as the cover 3 with a groove-shaped recess5, a dustproof C10- sure of the housing will be attained. For theelectric connection of the starting switch, three connecting terminals7, 8 and 9 are provided which extend through suitable slots It), 11, and12 in supporting plate 1 and are provided with bent-over portions 13,14, and 15 of a greater width and are secured to the support plate 1 bymeans of hollow rivets 16. The bent portion 13 has an angular part 17 onthe right edge of which an angular lever 13 is pivotably mounted, asshown in FIGURES 1 and 2. For this purpose, the angular lever 1's hastwo laterally notches 19 into which trunnionlike projections 2t? of theangular part 17 engage. These trunnionlike projections 20 are formed bya cutout into which the angular lever engages at the notches 19.

The longer arm 21 of the angular lever 18 carries a contact 22 which isoperatively associated with another contact 24 which is secured to acontact spring 23. The shorter arm of the angular lever 18 carries theright end of a heating wire 26 which is secured thereto by means of ascrew 25, as shown in FIGURES 1 and 2. Above the notches 19, the angularlever 18 is provided with a hollow, pressed-out pin 27, and oppositethereto a vertically bent portion 29 on the terminal strip 7 has asimilar hollow pin 28. These hollow pins 27 and 23 support resilientmeans comprising a compression spring 3t) which acts at one side uponthe angular portion 29 and at the other side upon the angular lever 13and serves for biasing and actuating the latter toward an operatingposition.

Contact spring 8 has an angular portion 31 on which, as shown in FIGURE4, contact spring 23 is secured by means of a rivet 32 and lockedagainst rotation by means of a pair of pins or projections 33 which arepressed out of the angular portion 31.

The heating wire conductor 26 is secured by a further screw 25 to anangular member or adjacent lever 34 which is pivotably mounted by meansof a slot 35 on the left end 36 of the bent portion 15 of terminal strip9 which is recessed in accordance with slot 35.

The other arm of the angular member 34 carries a set screw 37 which, asshown in FIGURE 5, engages upon the bent portion 15 of terminal strip 9.This bent portion 15 is bent again at an angle to form a tab 38 with acontact 39 thereon, as shown in FIGURE 5, which is operativelyassociated with contact For reinforcing the supporting plate 1, the sameis provided with a rib 4% which extends parallel to base plate 2 and maybe made integral with supporting plate I. Adjacent to a continuous bore4-1 for receiving the mounting screw rib 40 is provided with a thickerportion 42. Heating wire 25 is provided in the groove which is formedbetween base plate 2 and rib it). The angular portion I7 on which theanguiar lever 18 is pivotably mounted engages upon the right edge 43 ofrib 40 as shown particularly in FIGURE 3.

The operation of the switch as illustrated in the drawings may be bestdescribed with reference to FIGURE 8.

Terminal strip 7 of the starting switch is connected to one pole dd of asource of current, terminal strip 8 is connected to the auxiliary phasewinding 45 of a singlephase induction motor, and terminal strip 9 isconnected to the main winding 46 of this motor. The connecting point 4'7of the main winding 46 and the auxiliary phase winding 45 is connectedto a terminal 4% which may, for example, form the terminal strip or" amotor protective switch.

If the main switch is closed, heating wire 26 together with the mainwinding td which is connected in series therewith is supplied with thefull voltage so that the heating wire will be heated and expanded by thefuli current of the main winding. Spring 3h then pivots the angularlever 18 in a counterclockwise direction as seen in FF- URE 3 and itscontact 22 is then brought into engagernent with the associated contact24 of contact spring 23, as shown in FIGURE 3, the free end of whichwhen in the inoperative position engages upon a projection 1 ofsupporting plate 1. Consequently, the auxiliary phase or '7 startingwinding 45 also receives current so that the motor will start to run.The period required from the moment of switching on the motor to thestart of its rotation amounts to approximately one to two seconds.During the following starting procedure, contact 22 remains inengagement with the associated contact 24. As the speed of rotationincreases, the current in the main winding 46 decreases. As soon as thiscurrent in the main winding 46 has decreased approximately to thestrength of the rated current, the heat of heating wire will no longerbe sufficient to close the contacts and the auxiliary phase winding 45will be disconnected and remains disconnected for the entire period ofthe normal operative condition if during the operation the motor shouldbe overloaded, the auxiliary phase winding will again be connected tothe current so that it can operate as a torque support. During theoperation of the motor the heating wire will not be further heated sothat the return contact will remain constantly open and not cause anydisturbances, for example, of radio or television receptions.

If during the starting the heating wire 26 should become heated verystrongly and be expanded accordingly, contact 22 on the angular lever1.8 presses under the action of compression spring 39 the associatedcontact 24 upon contact 39 against the action of contact spring 23. Thisresults through the angular lever 1.3 and the engaging contacts 22, 2and 39 and the angular member 34 in a short-circuiting of heating wire26 so that the latter can cool, whereby any overheating or" the heatingwire will be reliably prevented. independently of this, the pair ofcontacts 22 and 24 remains further closed.

The switch according to the modification of the invention as illustratedin FIGURES 9 to 16 comprises a housing which consists of a plate 51 ofinsulating material and a housing cap 52 likewise of insulatingmaterial. Both housing parts 51 and 52 may be connected to each other byany suitable means. Housing plate 51 carries terminal strips 53, 54-,and 55 which are secured thereto by means of hollow rivets 56. Withinthe area of rivets 56, housing plate 51 has on its outside a reinforcingrib 51' integral therewith which provides the housin plate 51 with aconsiderable bending strength to resist the stresses which are caused bythe heating wire. Terminal strip 53 has a vertically bent portion 57 onwhich a contact 5% is secured. This contact 53 is operatively associatedwith a contact 59 which is rigidly secured to a contact-carrier Contactcarrier 66 consists of flat material and is provided with an aperture 61in order to reduce its weight. The edge 62 of aperture 61 serves as asupport of an arcuate leaf spring 63 which engages thereon under tensionwith one end which for this purpose is provided with a tongue 64 whichis pressed out of leaf spring 63 and bent in the direction toward thecontact carrier 6%. The opposite end of the arcuate leaf spring 63 ispivotably mounted in a substantially V-shaped aperture 65 in an angularlever 66. In order to prevent leaf spring 63 from sliding oii laterallywithin the V-shaped aperture 65, leaf spring 63 is provided on its rightend with projections 67, as shown in FIGURES 9, 11, and 12. By means ofthe inner edge 68 of aperture 61 contact carrier 66 engages into aV-shaped aperture 69 in the angular lever 66. Contact carrier 66 is thuspivotably mounted in this V-shaped aperture 69 of the angular lever 66.V

Underneath the V-shaped aperture 69, the angular lever 66 is providedwith lateral recesses '76 into which the edges 71 of an aperture 72 of avertically bent portion 73 of terminal strip 55 engage, as shown inFIGURE 13'. e

The angular lever 66 is thus pivotably mounted in the bent portion 75 ofthe terminal strip 55. The bent portion 73 is bent at an angle 74 onwhich resilient means comprising a compression spring 75, engages, theother end of which abuts against the angular lever 66 and biases ittoward an operating position thereof. By means of a mounting screw 76which is screwed into the angular lever 66 and a projection 76 of whichserves at the same time as a guide 8 for the compression spring 75, aheating wire 77 is secured to the angular lever 66. The other end of theheating wire 77 is secured to a slide member or adjust lever 79 by meansof a rivet 7 8.

The middle terminal strip 54- is provided with two vertical bentportions 8% and 81 which, as shown particularly in FIGURES 9 and 11,serve for guiding the slide member 79 Slide member 79 is provided with abent portion 32 which extends transverse to the direction of the heatingwire 77. A setscrew 83 is screwed into this cut portion 82 and engagesinto a recess 84 of the vertically bent portion of terminal strip 54-.If set screw 33 is actuated, slide member 79 will be shifted in thedirection of heating wire 77, whereby the heating wire will be eithertightened or released. Setscrew 33 also prevents slide member 79 fromsliding laterally in a direction vertical t0 the plane of FIGURE 9. Inorder to prevent slide member '79 also from tilting in the samedirection, the vertically bent portion 81 of terminal strip 54 isfurther provided with a vertically bent portion S5 which engages overthe inner end of slide member 79. The vertically bent portion 81 isfurther provided with a contact 36 upon which a screw 87 engages whenthe contact carrier 66 is in the disconnected position, and which isscrewed into the angular lever 66.

The diagram according to FIGURE 17 shows that the auxiliary phase 45 ofan electric motor is connected to the terminal strip 53, while one endof the main winding 46 is connected to the terminal strip 54. Bothwindings t5 and 46 are connected at 47 to a conductor 91 which may beconnected, for example, to a motorprotective switch. Terminal strip 55may be connected by a conductor 92 to the main current supply or to amain switch. According to the diagram as shown in FIGURE 18, theauxiliary phase 45 is likewise connected to the terminal strip 53. Theconnections for the conductor 52 and the main winding 4-6 are, however,reversed as compared with the diagram according to FIG URES 17.

While in the diagram according to FIGURE 17 only the current of the mainwinding 46 fiows through the heating wire 77, in the diagram accordingto FIGURE 18 the heating wire 77 must take up not only the current 01the main winding 46, but also the current of the starting winding 45.The circuit according to FIGURE 17 is generally applied to motors withhigh starting currents which are higher than three times the ratedcurrent while the circuit according to FIGURE 18 is applied to motorswith small starting currents which are smaller than three times therated current.

The operation of the starting switch as illustrated in FIGURES 9 to 18is as follows:

When the main switch is closed, the current flows through the mainwinding 46 as well as through the auxiliary winding 45', that is, asshown in FIGURE 17, through the contacts '53 and 59, the contact carrier66, the angular lever 66, the terminal strip 55, and, on the one hand,through the conductor 92, and on the other hand, through the terminalstrip 54, the slide member 79, the heating wire 77, the angular lever66, the terminal strip 55, and, the conductor 92. As soon as the motorhas reached its normal operative speed and heating wire 77 has beenheated and expanded sufiiciently, the angular lever 66 is pivotedcounterclockwise under the action of the compression spring '75 as shownin FIGURES 9, 11 and 17. As soon as leaf spring 63 exceeds its tiltingpoint it presses the contact carrier 6% upwardly as seen in thementioned drawings, and pivots the contact carrier suddenly into thedisengaging position as illustrated in FIGURE 11. The auxiliary winding45 is thus switched off. After this starts, the operating currentdecreases to its normal strength which is sufficient to maintain theheating wire' 77 V in the position as illustrated in FIGURE 11, in whichthe contact carrier 66 engages on a projection 93 which is integral withplate 51. If the main switch is opened,

the entire motor circuit will be interrupted. The main winding 46 aswell as the heating wire 77 will be without current so that heating wire77 can contract and thereby return the angular lever 66 against theaction of compression spring 75 to the position as indicated in FIGURES9 and 17. When leaf spring 63 exceeds its tilting point, contact 59 oncontact carrier 60 engages with the stationary contact 58. The startingswitch is then ready for a new starting operation.

If the heating wire 77 becomes strongly heated, setscrew 87 will engagewith contact 86 and thereby shortcircuit the heating wire 77 so that thelatter can cool off. This prevents the heating wire 77 from beingoverheated.

The operation of the starting switch illustrated in FIGURE 18 inconnection with the windings of an electric motor is the same as that ofthe switch according to FIGURE 17. As illustrated in FIGURE 19, it is,however, also possible to design the switch in such a manner that priorto the starting operation the contact carrier 60 will be in itsdisconnected position in which it engages upon a vertical projection 94which is integral with plate 51. Contact 59 and the associated contact58 are then, however, located on the opposite side of contact carrier60. If in this case the main switch is closed, a current fiows at firstonly through the main winding 46 and the heating wire 77 which is heatedby this current and will thus expand. Due to this expansion, the angularlever 66 will be able to pivot in a counterclockwise direction, wherebydue to leaf spring 63, the switch and thus also the auxiliary winding 45will be connected. The current then flows also through the auxiliarywinding 45 so that the motor will start. As soon as the motor hasreached its rated speed, the current flowing through the main winding 46will be reduced to a fraction of the starting current. This reducedcurrent will not be sufiicient to maintain the heating wire 77 in itsexpanded position. The heating wire will thus contract and thereby pivotthe angular lever 66 to its basic position, whereby due to leaf spring63 the contact carrier 60 will be moved to its disconnected position asshown in FIGURE 19, in which the contacts 58 and 59 are separated andthe auxiliary winding 45 is switched ofi. If in this event the motormight be overloaded during its operation, the auxiliary winding 45 willagain be switched on and will thus serve as a torque support.

Although my invention has been illustrated and described with referenceto the preferred embodiments thereof, I wish to have it understood thatit is in no way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed my invention, what I claim is:

1. A starting switch for a single-phase inducation motor having a mainwinding and a starting winding comprising, connect and disconnect meansfor connecting said starting winding in circuit with a source of powerfor energizing the starting winding to start the motor and for takingsaid starting winding out of circuit with said power source when saidmotor is operating substantially at rated speed corresponding to a givenload current in said main winding, said connect and disconnect meanscomprising a pivotally mounted lever having a long lever arm and a shortlever arm, a wire conductor connected in operation in series with saidmain winding and expandable longitudinally by current energizing saidmain winding, means connecting one end of said wire conductor to saidshort lever arm physically adjacent to a free end of said short leverarm for actuating said lever between two operating positions forrespectively connecting and disconnecting said starting winding, saidlong and short lever arms and said wire conductor being disposeddefining three sides of a rectangular configuration, said long lever armand said wire conductor being disposed substantially parallel, meanscomprising resilient means constantly applying a biasing force on saidlever for biasing said lever toward one of said two operating positions,adjust means disposed within said rectangular configuration for variablyadjusting tension on said wire conductor in opposition to said biasingforce to variably adjust said biasing force thereby to vary the value ofthe biasing force necessary for said resilient means to apply to saidlever to actuate said lever to said one operating position as said wireconductor expands and contracts in dependence upon the value of loadcurrent in said main winding and passing through said wire conductor,said adjust means comprising a displaceable, adjust lever disposedinteriorly of said rectangular configuration and connected to an end ofsaid Wire conductor opposite to an end connected to said short leverarm, means comprising a set screw interiorly of said rectangularconfiguration for adjus-tably displacing said adjust lever to variablyadjust said tension applied to said wire conductor to variably set saidbiasing force on said resilient means, means interiorly of saidrectangular configuration displaceably mounting said adjust lever, aplurality of contacts disposed interiorly of said rectangularconfiguration efifectively actuated to a closed condition and an opencondition by said lever arm when actuated to said two operatingpositions respectively for connecting and disconnecting said startingwinding, one of said contacts being disposed adjacent a free end of saidlong lever arm facing interiorly of said rectangular configuration,connections interiorly of said rectangular configuration and extendingoutwardly therefrom for connecting said contacts to said main andstarting windings of said motor and including connections for connectingsaid wire conductor in series with said main winding, whereby saidrectangular configuration substantially defines the dimensions of saidswitch and the values of said rated speed are accurately adjustable.

2. A starting switch according to claim 1, including protective meansrendered effective by said wire conductor and said lever for protectingsaid wire conductor and disposed interiorly of said rectangularconfiguration and including means comprising said contacts and saidadjust lever for by-passing said wire conductor electrically if the loadcurrent in said main current exceeds a given value and including meanscomprising said connections to maintain said switch in series circuitwith said main Winding.

3. A starting switch according to claim 2, in which said protectivemeans comprises means comprising other contacts and said adjust leverrendered effective by said lever and said wire conductor upon expansionthereof when said given value of load current is exceeded to continuesaid starting winding in circuit with said source of power to assistsaid main winding in torquing said motor.

References Cited in the file of this patent UNITED STATES PATENTS1,531,722 Adams Mar. 31, 1925 2,388,033 Berninger Oct. 30, 19452,418,235 Menzies Apr. 1, 1947 2,689,289 Bell Sept. 14, 1954 2,699,161Pees Jan. 11, 1955 2,839,634 Clark June 17, 1958 2,896,051 Taylor July21, 1959 FOREIGN PATENTS 505,726 France Oct. 5, 1920

1. A STARTING SWITCH FOR A SINGLE-PHASE INDUCATION MOTOR HAVING A MAINWINDING AND A STARTING WINDING COMPRISING, CONNECT AND DISCONNECT MEANSFOR CONNECTING SAID STARTING WINDING IN CIRCUIT WITH A SOURCE OF POWERFOR ENERGIZING THE STARTING WINDING TO START THE MOTOR AND FOR TAKINGSAID STARTING WINDING OUT OF CIRCUIT WITH SAID POWER SOURCE WHEN SAIDMOTOR IS OPERATING SUBSTANTIALLY AT RATED SPEED CORRESPONDING TO A GIVENLOAD CURRENT IN SAID MAIN WINDING, SAID CONNECT AND DISCONNECT MEANSCOMPRISING A PIVOTALLY MOUNTED LEVER HAVING A LONG LEVER ARM AND A SHORTLEVER ARM, A WIRE CONDUCTOR CONNECTED IN OPERATION IN SERIES WITH SAIDMAIN WINDING AND EXPANDABLE LONGITUDINALLY BY CURRENT ENERGIZING SAIDMAIN WINDING, MEANS CONNECTING ONE END OF SAID WIRE CONDUCTOR TO SAIDSHORT LEVER ARM PHYSICALLY ADJACENT TO A FREE END OF SAID SHORT LEVERARM FOR ACTUATING SAID LEVER BETWEEN TWO OPERATING POSITIONS FORRESPECTIVELY CONNECTING AND DISCONNECTING SAID STARTING WINDING, SAIDLONG AND SHORT LEVER ARMS AND SAID WIRE CONDUCTOR BEING DISPOSEDDEFINING THREE SIDES OF A RECTANGULAR CONFIGURATION, SAID LONG LEVER ARMAND SAID WIRE CONDUCTOR BEING DISPOSED SUBSTANTIALLY PARALLEL, MEANSCOMPRISING RESILIENT MEANS CONSTANTLY APPLYING A BIASING FORCE ON SAIDLEVER FOR BIASING SAID LEVER TOWARD ONE OF SAID TWO OPERATING POSITIONS,ADJUST MEANS DISPOSED WITHIN SAID RECTANGULAR CONFIGURATION FOR VARIABLYADJUSTING TENSION ON SAID WIRE CONDUCTOR IN OPPOSITION TO SAID BIASINGFORCE TO VARIABLY ADJUST SAID BIASING FORCE THEREBY TO VARY THE VALUE OFTHE BIASING FORCE NECESSARY FOR SAID RESILIENT MEANS TO APPLY TO SAIDLEVER TO ACTUATE SAID LEVER TO SAID ONE OPERATING POSITION AS SAID WIRECONDUCTOR EXPANDS AND CONTRACTS IN DEPENDENCE UPON THE VALUE OF LOADCURRENT IN SAID MAIN WINDING AND PASSING THROUGH SAID WIRE CONDUCTOR,SAID ADJUST MEANS COMPRISING A DISPLACEABLE, ADJUST LEVER DISPOSEDINTERIORLY OF SAID RECTANGULAR CONFIGURATION AND CONNECTED TO AN END OFSAID WIRE CONDUCTOR OPPOSITE TO AN END CONNECTED TO SAID SHORT LEVERARM, MEANS COMPRISING A SET SCREW INTERIORLY OF SAID RECTANGULARCONFIGURATION FOR ADJUSTABLY DISPLACING SAID ADJUST LEVER TO VARIABLYADJUST SAID TENSION APPLIED TO SAID WIRE CONDUCTOR TO VARIABLY SET SAIDBIASING FORCE ON SAID RESILIENT MEANS, MEANS INTERIORLY OF SAIDRECTANGULAR CONFIGURATION DISPLACEABLY MOUNTING SAID ADJUST LEVER, APLURALITY OF CONTACTS DISPOSED INTERIORLY OF SAID RECTANGULARCONFIGURATION EFFECTIVELY ACTUATED TO A CLOSED CONDITION AND AN OPENCONDITION BY SAID LEVER ARM WHEN ACTUATED TO SAID TWO OPERATINGPOSITIONS RESPECTIVELY FOR CONNECTING AND DISCONNECTING SAID STARTINGWINDING, ONE OF SAID CONTACTS BEING DISPOSED ADJACENT A FREE END OF SAIDLONG LEVER ARM FACING INTERIORLY OF SAID RECTANGULAR CONFIGURATION,CONNECTIONS INTERIORLY OF SAID RECTANGULAR CONFIGURATION AND EXTENDINGOUTWARDLY THEREFROM FOR CONNECTING SAID CONTACTS TO SAID MAIN ANDSTARTING WINDINGS OF SAID MOTOR AND INCLUDING CONNECTIONS FOR CONNECTINGSAID WIRE CONDUCTOR IN SERIES WITH SAID MAIN WINDING, WHEREBY SAIDRECTANGULAR CONFIGURATION SUBSTANTIALLY DEFINES THE DIMENSIONS OF SAIDSWITCH AND THE VALUES OF SAID RATED SPEED ARE ACCURATELY ADJUSTABLE.